UML for Embedded Systems III. Detailed Design - Eurecomsoc.eurecom.fr/UMLEmb/Course_UML_III_Behavior.pdf · UML for Embedded Systems III. Detailed Design Ludovic Apvrille [email protected]

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UML for Embedded SystemsIII. Detailed Design

Ludovic [email protected], Office 470

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Memo on Methodology

I. AnalysisUse case

First class diagramRelevant scenarios

II. DesignClasses of the system

Architecture of the system

III. Detailed designBehavior of the system

IV. Validation of the system

SimulationCode generation

(C) Ludovic Apvrille UML for Embedded Systems - Fall 2012

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Detailed Design Stage

� Purpose• Design the behavior of classes

� State machine diagrams• Signal sending• Signal receiving• Composite states• Loop, tests• Setting and use of variables• Etc.


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Detailed Design

� Basics of automata� Modeling objects with states machines� UML state machine diagram� TAU G2 state machines� Examples


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Basics of Automata

� Definition• Machines whose input behavior is not only a direct

consequence of the current input, but of some past history of its input

� Characterized by an internal state• Current state = past experience


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Example of State Machine Diagrams

LampOffLampOff

lampOnlampOn

on()on() off()off()

Start state

States

Trigger


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Output and Actions

� Actions can be generated either at state entrance, exit or at trigger level

LampOffLampOff

lampOnlampOn

on()/print("on");on()/print("on"); off()off()

Mealy automaton

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Use of Variables

LampOffLampOff

lampOnlampOn

on()/ctr = ctr+1;on()/ctr = ctr+1; off()off()

Integer ctr;Integer ctr;


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Mealy Machines


� Mealy machines• Hopcroft and Ullman (1979, 42), Salomaa (1973, 31)• Finite-state machines

- Take a string on an input alphabet

- Producing a string of equal length on an output alphabet.

� Formally, a Mealy machine is a six-tuple M = (Q, Σ, Γ, δ, λ, q1)• where

- Q = (q1, q2, …, q|Q|) is a finite set of states;

- Σ = (σ1, σ2, …, σ|Σ|) is a finite input alphabet;

- Γ = (γ1, γ2, …, γ|Γ|) is a finite output alphabet;

- δ : Q x Σ → Q is the next-state function, such that a machine in state qj, after reading symbol σk, moves to state δ(qj, σk) ∈ Q

- λ : Q x Σ → Γ is the output function, such that a machine in state qj, after reading symbol σk, writes symbol λ(qj, σk) ∈ Γ ; and

- q1 ∈ Q is the initial state in which the machine is found before the first symbol of a string is processed

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Example

� Let M = (Q, Σ, Γ, δ, λ, q1) with• Q = {q1, q2}• Σ = {sig1, sig2}• Γ = {out1, out2}• δ(q1, sig1) = q1; δ(q1, sig2) = q2; • δ(q2, sig1) = q2; δ(q2, sig2) = q1;• λ(q1, sig1) = out1; λ(q1, sig2) = out2; • λ(q2, sig1) = out2; λ(q2, sig2) = out1;

� Propose a graphical representation of this machine


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Detailed Design



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What Can be Modeled with State Machines?

� State machines are well-suited for the modeling of event-driven and discrete behavior

� Inappropriate for modeling continuous behavior

� Are State Machines well-suited for modeling real-ti me and embedded systems?• What is an event-driven systems?• What are real-time and embedded systems?

timetime

thresholdthreshold


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Event-Driven Behavior

� Event = a type of observable occurrence• Interactions

- Invocation of object operations is synchronous (call event)

- Receiving of asynchronous signal (signal event)

• Occurrence of time instants (time event)- Interval expiry

- Calendar/clock time

• Change in value of some entity (change event)� Event Instance = an instance of an event (type)

• Occurs at a particular time instant and has no duration


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Embedded Systems’ Architecture

� Embedded system = controlling system + controlled system + environment

Controlling Controlling SystemSystem

SensorsSensorsSensorsSensorsSensorsSensorsSensorsSensorsSensorsSensorsActuatorsActuators

Controlled Controlled SystemSystem

Interface


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Event(Input)

Response to External Events

Embedded Embedded SystemSystem

Response(Output)

Synchronous

Asynchronous

Single event

Multiple event

Synchronous

Asynchronous

Single event

Multiple event

External Hostile Environment


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What is a Real-Time System?

� Real-Time Systems have been defined as:“Those systems in which the correctness of the system depends not only on the logical results of t he computation, but also on the time at which the resu lts are produced”

(J. Stankovic, “Misconceptions About Real-Time Computing”, IEEE Computer, 21(10), October 1988)


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Jobs and Tasks

� Task• A task is a set of related jobs joined to provide functions

� Job• A job is a unit of work, scheduled and executed by the

system� Parameters

• Temporal behavior- Last less than 20ms, periodic task i.e. executes every 30 ms

• Functional: intrinsic properties of the job- Taps of filter

• Resource requirements- 10kb of memory

• Interconnection: its communication with other jobs- The decoding job must send its result to the displaying job- May use shared memory, message queues, etc.


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Event(Input)

Response to External Events

RealReal--Time Time SystemSystem

Response(Output)

Timing ConstraintsSynchronous

Asynchronous

Single event

Multiple event

Synchronous

Asynchronous

Single event

Multiple event


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Are State Machines Well-Suited for Modeling Real-Time and embedded Systems?


� What do you think?

� What should be modeled with state machines?• In principle, anything that manifests event-driven behavior

• In practice:- The behavior of individual objects

- Object interactions

� The dynamic semantics of UML state machines are currently mainly specified for the case of active objects

� Note: currently, there is no support in UML for modeling continuous behavior

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Object Behavior: General Model

Initialization

Sending output

Termination

Computing input

Waiting for input

Note: this is not a UML state machine but rather a flowchart to explain how an object generally behaves


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Example

LampOffLampOff

lampOnlampOn

on()/print(on); off()off()

stopLamp()stopLamp()

Initialization

Sending output

Termination

Computing input

Waiting for input


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Active and Passive Objects

� An active object is a thread of control of the application• Autonomous• No internal concurrency• Mechanisms for storing input data

� A passive object is an object which is not active• It is activated by external power


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Object Behavior: Active Objects

Initialization

Sending output

Termination

Computing input

Waiting for input


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Object Behavior: Passive Objects

Initialization

Sending output

Termination

Computing input

Waiting for input


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Passive Objects: Synchronization Issues

Initialization

Sending output

Termination

Computing input

Waiting for input

Synchronization may be

required!


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V. Detailed Design



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Basics of UML State Machine Diagrams


� States

� Transitions

� Transition with temporal information

s1 s2Message [condition] / action

after(100)E1 E2

when (date = 10)E1 E2

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States, Transitions and Actions

off/printf(“needless”);off/printf(“needless”);

off/printf(“to off”);off/printf(“to off”);LampOffLampOff

entry/lamp.off();entry/lamp.off();

exit/printf(“exiting”);exit/printf(“exiting”);

LampOnLampOn

entry/lamp.on();entry/lamp.on();


LampOffLampOff

entry/lamp.off();entry/lamp.off();exit/printf(“exiting”);exit/printf(“exiting”);off/nulloff/null

Self transitionentry and exit

actions are ignored


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UML 2.x State Machines: Towards SDL

state1state1

signal2()signal2()

signal1()signal1()

state2state2

Waiting for the receiving of signal signal1

Sending of signal signal2


Guards

state1state1

signal2()signal2()

signal1()signal1()

state2state2

x = x +1;x = x +1;

Integer x;Integer x;

x <5x <5x = 5x = 5

LampOffLampOffentry/lamp.off();entry/lamp.off();


LampOnLampOnentry/lamp.on();entry/lamp.on();


on[LampIsPlugged]/printf(“to on”);on[LampIsPlugged]/printf(“to on”);


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State2.1State2.1

Composite States: Hierarchical State Machines

State1State1

State2.1State2.1State2.1State2.1

State2.2State2.2State2.2State2.2

State3State3

H

H*

Swallow historyDeep history


H

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Order of Actions

S1S1exit/exS1exit/exS1

S2S2entry/enS2entry/enS2

initS2initS2E/actEE/actE

Execution sequence when E:

exS11 � exS1 � actE � enS2 � initS2 � enS21

S21S21entry/enS21entry/enS21

S11S11exit/exS11exit/exS11


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Orthogonal Regions

oven off

oven lighton

oven lightoff

oven on


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Deferred Events

� Events can be deferred if they cannot be computed• Saved for future use

off/off/

LampOnLampOn

entry/lamp.on()entry/lamp.on()

on/on/

LampOffLampOff

entry/lamp.off()entry/lamp.off()off/deferoff/defer

Event is deferred


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Fork and Join Transitions

StaffStaffMemberMember

employeeemployee

ChildChild AdultAdult RetireeRetiree

ageage

ManagerManagerManagerManager


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Detailed Design

� Basics of automata� Modeling objects with states machines� UML state machine diagram� With TAU G2� Examples


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States Machines under TAU G2

state1state1

signal2()signal2()

signal1()signal1()

state2state2

x = x + 1;x = x + 1;

Integer x;Integer x;

x <5x <5x = 5x = 5

signal3()signal3()

signal3signal3

Deferred signal

Termination of the object


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Detailed Design

� Basic of automata� Modeling objects with states machines� UML state machine diagram� TAU G2 state machines� Examples


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Counter


statemachine initializeStatechart Diagram {1/1}statemachine initializeStatechart Diagram {1/1}

initinitInteger value;Integer value;

valuevalue

[true][true]

All transition should have a condition for being triggeredAll transition should have a condition for being triggered

Loop(value)Loop(value)

<5<5

value = 0;value = 0;

initinit

elseelse

value = value + 1;value = value + 1;

Counter

Counter

<<interface>>

fromCounter

Loop (Integer)

<<interface>>

fromCounter

Loop (Integer)

port1port1

fromCounterfromCounter

<<signal>>

Loop

Integer

<<signal>>

Loop

Integer

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Counter: Trace Obtained at Simulation Step

Counter[1]

Counter[1]

env[1]

env[1]

Sequence diagram tracegenerated by Taufor Counter

Sequence diagram tracegenerated by Taufor Counter

initinit

Loop(1)Loop(1)

initinit

Loop(2)Loop(2)

initinit

Loop(3)Loop(3)

initinit

Loop(4)Loop(4)

initinit

Loop(5)Loop(5)

initinit


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Alarm Clock


Alarm

Alarm'port''port'

SetSet BellBell

<<signal>>

Bell<<signal>>

Bell<<signal>>

Set<<signal>>

Set

statemachine initialize {1/1}

waitForSetwaitForSet

Set()Set()

timer myTimer; timer myTimer;

set(myTimer(), now+10);set(myTimer(), now+10);

waitForTimerwaitForTimer

myTimer()myTimer()


Bell()Bell()

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Simulation of Alarm Clocksd Trace (7) interaction UseCase3 {1/1}sd

Alarm[1] Alarm[1]

env[1]

env[1]

Trace (7) interaction UseCase3 {1/1}Sequence diagram tracegenerated by Taufor Alarm

Sequence diagram tracegenerated by Taufor Alarm

'@Set' ()'@Set' ()


myTimer () /* 10.0000 */myTimer () /* 10.0000 */

waitForTimerwaitForTimer

myTimer ()myTimer ()

Bell ()Bell ()



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Exercises: Ping-Pong Game

� Two players P1 and P2� P1

• Sends value k to P2• Waits for value k• Increment k• And so on..

� P2• Waits for a value x• Returns x to the sender


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Microwave Oven

� We wish to model a basic oven with a door and a « start » button

� Once a meal has been put in the oven, the user pushes the « start » button. Once pushed, the meal is heated for 30 seconds. Then, the oven stops and plays a bell sound

� Alternatively, the user may open the door while the oven is heating. In that case, the heating process stops and the 30s delay is set to 0

« Start » button


Documents

UML for Embedded Systems III. Detailed Design - Eurecomsoc.eurecom.fr/UMLEmb/Course_UML_III_Behavior.pdf · UML for Embedded Systems III. Detailed Design Ludovic Apvrille [email protected]